The present invention relates to the technical field of networks for transporting energy fluids or signals. These transport networks comprise installations duct elements connected end to end and inside which cables, pipes or wires are laid. A network such as this may be underground or underwater.
The present invention relates more particularly to a sealing terminal for an installations duct, or an installations duct element.
The term xe2x80x9cinstallations ductxe2x80x9d is intended to mean any plastic tube, for example made of high-density polyethylene (HDPE), which is sealed with respect to the outside against liquids, and with respect to the inside, against any fluid, including one under pressure. A tube such as this is also rigid enough to mechanically withstand any load, such as the weight of a head of earth due to the installations duct being buried, and flexible enough to be handled, for example would into a drum.
To store or transport the installations duct elements before they are connected, these may be filled with a liquid, for example air under pressure, for example at 0.5 bar, then plugged at their two respective ends. This in particular makes it possible to counter the weakening of said ducts which is associated with the increase in their temperature, for example when exposed to the sun.
Part of the problem is that installation ducts, for example of tubular shape, made of a plastic of the HDPE type, are generally black in color.
The duct elements are often stored or transported out of doors, and their black color encourages them to absorb radiation from the sun, thus encouraging them to heat up. It is not rare for such ducts to reach temperatures of the order of 60xc2x0 C., thus causing the material of which they are made to soften.
This increase in temperature therefore weakens the duct elements, which may become crushed, particularly when they are piled up on a storage area or on a truck. The internal pressurization makes it possible to avoid this problem of crushing, but this heating-up substantially raises the pressure inside these ducts. By way of example, the internal pressure may reach 3 to 5 bar.
The plugging means used at the two ends have therefore to withstand high internal pressures, and the seal against the inside has to be maintained for such pressures.
The object of the present invention therefore is to seal installations duct elements in a simple way so that during their transport and storage they can withstand high mechanical stresses and, in particular, high internal pressures.
The object assigned to the present invention is achieved by means of a sealing terminal for a tubular installations duct.
According to the invention, the sealing terminal comprises:
a plug comprising a threaded frustoconical part, the screw thread of which is, for example, self-tapping, which can be screwed into one end of the duct,
a manipulating head with a peripheral shoulder in the continuation of the plug, said peripheral shoulder being designed to face an edge face of the border around an opening of the duct,
and an annular seal arranged against the peripheral shoulder.
The object assigned to the present invention is also achieved using a method for plugging a plastic tubular installations duct for storage and transport, consisting in plugging in a sealed manner the ends of the pressurized duct or duct intended to be pressurized.
According to the invention, the method consists in
cutting the end of the duct transversely to its longitudinal axis (y-yxe2x80x2) so as to obtain an edge face whose annular surface, with no roughnesses, lies in a plane orthogonal to the longitudinal axis (y-yxe2x80x2),
in using a sealing terminal according to any one of claims 1 to 8 for said end of the duct,
in screwing the plug into the corresponding end of the duct in an axial direction (F),
and in compressing the annular seal between the peripheral shoulder and the corresponding edge face (1a) in the axial direction (F), to finish the screwing operation of the previous step.
One advantage of the sealing terminal according to the invention lies in the fact that it allows sealing to be achieved on the outside of the duct, thus increasing the simplicity of construction and its reliability.
Another notable advantage lies in the fact that the sealing terminal makes it possible to maintain the seal even when it is subjected to high pressures.
Another advantage lies in the fact that the sealing is achieved on the edge face of the duct, which is capable of withstanding a high axial load from the sealing terminal.
Another advantage of the sealing terminal is associated with its great simplicity of use.